1. Field of the Invention
The present invention relates to a radiation image detecting device for use in a medical diagnosis device, a non-destructive testing device, or the like.
2. Description of the Related Art
Recently, digital radiation image detecting devices have appeared, which are typified by a computed radiography (CR) and a flat panel detector (FPD). These devices can directly obtain digital radiation images and cause image display devices, such as a cathode-ray tube and a liquid crystal panel, to display the images. Consequently, the digital radiation image detecting devices have considerably enhanced the convenience of diagnostic operations in hospitals, clinics, and the like.
Further, a flat panel detector (FPD) has been developed which uses thin-film transistors (TFTs) or charge-coupled devices (CCDs), as a new digital radiation image technique.
Regarding these radiation image detecting devices, a radiation image detecting device is known, which has an imaging panel formed by bonding together a sensor panel (planar light-receiving device) on which light-receiving elements, such as thin-film transistors (TFTs) or charge-coupled devices (CCDs), are arranged two-dimensionally, and a scintillator panel in which a scintillator layer for converting radiation into light detectable by the light-receiving elements is formed on a support.
It is disclosed that the above radiation image detecting device is equipped with the sensor panel, the scintillator layer for converting radiation into light, and a scintillator protecting member made of a hot-melt resin (see, e.g., Patent Document 1). The Patent Document 1 describes that a scintillator panel and a sensor panel are bonded together via a scintillator protecting layer made of a hot-melt resin. Patent Document 2 discloses a radiation image detecting device having an imaging panel formed by bonding together a scintillator panel and a sensor panel via a hot-melt resin serving as an adhesive layer.
Here, both of the Patent Documents 1 and 2 describes that a material made of CsI(Tl) having a columnar crystal structure is used as a scintillator layer. Generally, such a scintillator layer is formed by a gas-phase method. However, when a scintillator layer having a large size of, e.g., 430 mm×430 mm is formed by a gas-phase method, a film-thickness distribution inevitably occurs in plane. And, when the scintillator layer having a film-thickness distribution is adhesively bonded to the flat sensor panel, the distance between both of the layers is uneven in plane due to the film-thickness distribution in the scintillator layer. Thus, image irregularity occurs. In addition, a thin-film-thickness part of the scintillator layer is difficult to be intimately bonded to the adhesive layer. Accordingly, there is a problem that the thin-film-thickness part of the scintillator layer peels off the adhesive layer. From the viewpoint of image quality, the thinner the adhesive layer, the better. However, the thinner the adhesive layer, the more serious the above problem.